1. Field of the Invention
The present invention relates to a rotary cutter for cutting a continuous corrugated strip into strip sections having variable lengths. More particularly, this invention is applicable to a rotary cutter for shearing a metallic corrugated strip into sections which are used as corrugated fins in the manufacture of automobile radiators.
2. Description of the Related Art
Certain types of automotive radiator cores include corrugated fins welded or soldered to water tubes. Corrugated fins are obtained by passing a continuous metallic strip between a pair of toothed forming rollers or wheels to form a continuous corrugated strip, which is then sheared by a cutting machine into sections having a desired length. For the manufacture of radiators on a mass production basis, it is desirable for a cutting machine to operate at as high a speed as possible to shear a corrugated strip discharged continuously and at a high speed from the forming rollers. Another requirement for cutting machines is the capability of shearing the corrugated strip into a desired length, which may vary depending upon the size of the radiator cores to be manufactured. A further requirement is to cut the corrugated strip precisely at a desired shearing point in order to obtain a series of strip sections having a uniform length.
U.S. Pat. No. 4,685,318 issued to Ueda et al. illustrates an example of a conventional cutting apparatus. This type of apparatus is called a rotary cutter and has a toothed wheel and a rotary drum which are rotated in synchronization with each other. A fixed cutter blade is disposed in the toothed wheel and a movable cutter blade is disposed in the rotary drum. The continuous corrugated fin passes between the toothed wheel and rotary drum and is sheared in a predetermined length by pushing the movable cutter blade toward the fixed cutter blade like a guillotine.
In this conventional apparatus, it is required that both cutter blades be shaped and assembled accurately because both cutter blades are engaged at one point on which the outer circles of the toothed wheel and the rotary drum are in contact with each other. Therefore, production costs of the conventional apparatus are high. Another problem is that the edges of the cutter blades are worn away in a short period because each edge of the cutter blades is engaged with the other at a high speed. The worn edge causes the cutting condition of the cutters to worsen. The further problem is that the guillotine type cutter is capable of cutting corrugated fins made of low-ductility materials such as aluminum but is not capable of cutting fins made of high-ductility materials such as copper, thin corrugated fins, or wide corrugated fins.